Abstract Chalcogenide glass (ChG) Ge 22 Se 58 As 20 is a significant material in infrared optical systems, and it is usually machined by ultraprecision single point diamond turning (SPDT) for aspheric lens and freeform surface. However, as a soft brittle material, the surface is easily cracked during cutting. With the increasing demand for imaging quality, the surface integrity of chalcogenide glasses becomes increasingly important. This paper proposes a method to achieve high-precision and high-efficiency aspheric lens by SPDT. First, to study the material properties, the Vickers hardness of Ge 22 Se 58 As 20 is tested, and the element components and microstructure are analysed by EDS. Second, through orthogonal cutting, the critical cutting thickness of the brittle-ductile transition is tested to be 1.2 μm and the minimum depth of cut for chip formation of 100 nm is identified. The material removal rate under ductile machining in face turning was calculated. Finally, by optimizing the machining condition, an aspheric lens with surface roughness of Ra 6.47 nm and form error of PV 120.82 nm was successfully fabricated.
Last. Huimin Gao(TJU: Tianjin University)H-Index: 6
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Freeform optics has been regarded as the next generation of the optical components, especially those with non-circular apertures are playing an increasingly significant role in scanning field and specialized optical system. However, there still exist challenges to machine non-circular optical freeform surface. This paper is focused on highly efficiently generating freeform surfaces with optical surface quality by ultra-precision turning using a fast tool servo (FTS). A systematic strategy of mac...
Abstract Microlens arrays of single-crystal silicon are required increasingly in advanced IR optics. In this study, we attempted to machine spherical concave microlens arrays on a single-crystal silicon wafer by slow tool servo diamond turning. The form error, surface topography, material phase transformation, and cutting force characteristics were investigated experimentally. It was found that brittle fracture occurred preferentially at one side (the exit side of tool feed) of the lens dimples ...
Pulling a sphere and vibrating it around an equilibrium position by amplitude-modulation in the near-field of a single finite circular piston transducer is theoretically demonstrated. Conditions are found where a fluid hexane sphere (with arbitrary radius) chosen as an example, centered on the axis of progressive propagating waves and submerged in non-viscous water, experiences an attractive (steady) force pulling it towards the transducer, as well as an oscillatory force forcing it to vibrate b...
Glasses deform permanently as a result of indentation and the total resistance to deformation consists of three individual resistances, i.e., those to elastic deformation, densification, and plastic flow. The link between Vickers hardness and the resistances to densification and plastic flow has been investigated previously, but the link between the resistance to elastic deformation and hardness has not yet been studied. In this work, we investigate the link between elastic deformation during in...
#1Peng Jia(CAS: Chinese Academy of Sciences)H-Index: 2
In diamond cutting of optical glasses, the magnitude of critical depth of cut for brittle-ductile transition is an important factor affecting the machinability of the work material in terms of production rate and surface quality. In this work, scratching tests with increasing depths of cut were conducted on glass BK7 to evaluate the influence of the cutting fluid properties on the critical depth of cut. Boric acid solutions of different concentrations were selected as cutting fluids in the tests...
Abstract In this experimental study, diamond turning of single crystal 6H-SiC was performed at a cutting speed of 1 m/s on an ultra-precision diamond turning machine (Moore Nanotech 350 UPL) to elucidate the microscopic origin of ductile-regime machining. Distilled water (pH value 7) was used as a preferred coolant during the course of machining in order to improve the tribological performance. A high magnification scanning electron microscope (SEM FIB- FEI Quanta 3D FEG) was used to examine the...
#1Bin Tang(CAS: Chinese Academy of Sciences)H-Index: 5
#2Yi Yang(CAS: Chinese Academy of Sciences)H-Index: 2
Last. Long Zhang(CAS: Chinese Academy of Sciences)H-Index: 30
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The germanate glass ceramics is a potential candidate material for infrared (IR) dome and window applications. The crystallization mechanism of 20BaO-10Ga 2 O 3 -70GeO 2 glass was investigated by differential thermal analysis (DTA), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Two different types of phase evolution were found in the early stage of crystallization: (1) the further growth of the microcrystal formed during the slow cooling of glass melt and (2) the glass-in-glass...
Abstract The size effect in metal cutting is evident in the nonlinear scaling phenomenon observed in the specific cutting energy with decrease in uncut chip thickness. It has been argued by many researchers that this scaling phenomenon is caused mainly by the cutting tool edge radius, which purportedly affects the micro-cutting process by altering the effective rake angle, enhancing the plowing effect or introducing an indenting force component. However, the phenomenological reasons why the tool...
Compared to oxide-based glasses, vitreous materials involving chalcogens form a rather new family of glasses which have received attention, mainly because of their transmission in the mid-infrared. Indeed as low phonon compounds, these heavy-anion glasses allow the fabrication of molded optics for infrared cameras as well as infrared fibers operating in a large spectral range. These waveguides, when correctly tapered, allows the development of a new generation of sensitive evanescent-wave optica...
Abstract The deployment of cup wheels to precision-grind optical glass, offers both considerable economic advantages and significant increases in flexibility. In this contribution, the material removal mechanisms of the grinding process will be analysed on the basis of material-specific characteristics. Attention will focus on the transition phase from brittle to ductile chip formation. The first step in which the process model engages, is the identification of process-determining model componen...
Abstract In this research work, we have described the model-fitted and model free approaches for the study of crystallization kinetics in Se85Te15-xBix chalcogenide glasses. Se85Te15-xBix bulk alloys were synthesized by melt quenching technique. High Resolution X- Ray diffraction (HRXRD) was used to confirm the amorphous nature of prepared alloys. Non-isothermal Differential Scanning Calorimetry (DSC) measurements were done at heating rates of 5, 10, 15, 20 and 25 K/min for crystallization kinet...
#1Xinfang Huang(USTL: University of Science and Technology, Liaoning)H-Index: 4
#2Zhiwen Xie(USTL: University of Science and Technology, Liaoning)H-Index: 6
Last. Di Wu(USTL: University of Science and Technology, Liaoning)H-Index: 1
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Abstract CrWN glass molding coatings with different W contents were synthesized by plasma enhanced magnetron sputtering (PEMS). The microstructure, mechanical, wear resistance, and anti-oxidation properties of as-deposited coatings were investigated using various techniques and tests. The results showed that the as-deposited coatings exhibited typical columnar growth structure, consisting of layered CrN and W2N, and showed increased lattice expansion and hardness enhancement with increasing W co...
CrWN glass molding coatings were deposited by plasma enhanced magnetron sputtering (PEMS). The microstructure and thermal stability of these coatings were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscope, transmission electron microscope, atomic force microscope and nanoindentation tests. The as-deposited coating exhibited an aggravated lattice expansion resulting in a constant hardness enhancement. The vacuum annealing induced surface coarsening ...
Abstract The CrWN glass molding coating was synthesized by plasma enhanced magnetron sputtering (PEMS). The effect of annealing environment (e.g., vacuum, N2 and Air) on the microstructure and mechanical property of as-deposited coating was investigated by the X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic force microscope (AFM) and nanoindentation tests. Results showed that the as-deposited coating exhibited dense columnar structure c...
Chalcogenide glasses (Ge10As40Se50) are one of the core components of the athermalized infrared optical system. Because of material properties, its processability is limited, and surface defects are difficult to control. The chemical nature of Ge10As40Se50 has been established, which can react with sodium hydroxide and hydrogen peroxide (H2O2). In this paper, experimental studies are further carried out to investigate the effect of chemical-mechanical polishing on the surface. As a result, both ...
